Magnet-steel



'UNITED STATES PATENT OFFICE.

KOTARO HONDA, OF YONEGA-FUKUBO, SEND AI, JAPAN, ASSIGNOR TO SUMITOMOOHUKOSHO, LTD, OF OSAKA, JAPAN, A CORPORATION OF TAP-AN.

MAGNET-STEE 1,338,132.. Ili'o Drawing.

To all whom it may concern:

Be it known that I, KOTARO HONDA. D. Sc.,

citizen of Ja an, reslding at No. 21 Kanoko Shimidzu, onega-fukuro,Senda1, Japan,

have invented certain new and useful Improvements in Magnet-Steel; and Ido here by declare the fol owi td be a full, clear,

and exact description the invention, such as will enable others skilledin the art to which it appertains to make and use the same. i

This invention relates .to steels and to magnets made therefrom.

novel vma net ore particularly, the invention relates to 'themanufacture of permanent magnets from alloys comprising carbon steel,cobalt, and one or more metals of the chromium family.

Magnets made accordance with the in-' vention materially excel ma etsheretofore known especiallvin point 0 strong residual magnetism and argecoercive force.

In the particular embodiment of the invention here chosen for purposesof illustrating and explainingl the Ibtroarli pringiple? epa lcuarme a0' involved, tungsten is t the chromium group. constituting an essentialingredient of the alloy, the use of chromium in addition to tungstenbeing very desirable but not essential. Inm copending application,Serial No. 197,838, led October 22,1917, is disclosed and claimedanother specific embodiment of the invention in which chromium is theonly metal of the chromium roup specified as an essential ingredienfl othe magnet steel in question;

.while in'an'other copending application Serial No. 197,839,filedOctober 22, 1917, is disclosed and claimed another specific embodimentof the invention in WhlCll molybdenum, and optionally chromium, arespecified as ingredients of the alloy steel. In a typical instance, amagnetembodying the principles of the invention may be made of an alloysteel having the following ran e of composition:

obalt, 5-60%'; tungsten, 110%; chromium, (15-10% carbon steel, (with0.52% carbon,) the remainder. Most desirably the cobalt content is from20 to 60%, and,35% has been found particularly suitable.- The chromium,althou 'h a desirable constituent,

' may be omitted without seriously diminish- Specification of LettersPatent. Patented Apr. 27, 1920. Application filed October 22, 1917.Serial No. 197,837.

temperature for ordinary magnet steel which i is about 800 C. Afterquenching, the

,shaped body of paramagnetic metallicmaterial is strongly magnetlzedwith the aid of a owerful magnet or coil.

he ma et produced in the manner described is ar superior to inagnetsheretofore known in the art, particularly as regards (l) Coercive forcewhich in magnets of the best ty' e heretofore known. does not exceed C.magnet, the specific coercive force reaches S. units, whereas in thepresent 200 C. G. S. units. For this reason, loss of magnetism orso-called magnetic decay, due

to" shock or lapse of time is exceedingly small in the case of thepresent magnet.

(2) Intensity of magnetization per unit volume, which in the knownmagnets of the best type rarely exceeds 450 C. G. S; units afterartificial aging; Whereas owing to its lar e coercive force theintensity of mag netlzation of the Grpresent magnet commonly exceeds 700C. S. units after artlficial aging.

The foregoing remarkable distinguishing characteristics of my new magnetobviously render the same capable of wide use to an increased extent inarts in which the magnet pla san important part.

at I claim is: 1. A method of preparing permanent magnets-whichcomprlses' quenching a body of paramagnetic alloy steel containingcobalt at a .temperature substantially above 800 -C., and thereaftermagnetizing the same.

. 2. The methodof preparing permanent- .magnets which COIIIPI'lStESquenching a body of an alloy steel containing from about 5 to 60 percent. cobalt, from aboutal to 10 per cent. tungsten, and fromabout 0.5to 10 per I cent. chromium, at a temperature substantially above 860 0.,and thereafter mag 5. The metbo of preparing permanent magnets whichcomprises quenching at a temperature substantially above 800 C. a bodyof an alloy steel containing cobalt and aiggsten and thereaftermagnetizing said 6. The method of preparing permanent magnets whichcomprises uenchin'g at a temperature substantially a ove 800 C. a

body of .an alloy steel containin cobalt, tungsten and chromium, and tereafter magnetizing said body.

7 In a method of reparing permanent magnets, the step whic COIHPI'ISBSqueching a body of paramagnetic alloy steel containin-gcobalt at atemperature substantially above 800 C.

8. In a method of I magnets, the step whic comprisesquenching a body ofan alloy steel containing cobalt and a metal of the chromium group, at atemperature approximating 1100 C.

reparing permanent 9. As a new article of manufacture, a

. magnetized body of an alloy steel contaim cobalt and a metal of thechromium g group;

10. As a new article of manufacture, a magnetized body of an alloy steelcontaining cobalt and tungsten. a

11. As a new article of manufacture, a magnetized body of an alloysteelcontaining cobalt, tungsten and chromium.-'

12.]As anew article of manufacture, a permanent ma et made of .an alloy"con taining from a out 5 to 60 per cent. cobalt, from aboutl to 10 percent. t n, and carbon. steel of from about 0.5 to per cent. carbon.

13. new article of manufacture, a

permanent ma 'tainingfrom a out 5 to 60 per cent. cobalt, from about 1to 10 percent. tungsten, from at madev of an alloy conabout 0.5 to 10per cent. chromium, and carbon steel of from about 0.5 to 2 per cent.carbon".

14:. As a new article of manufacture, a

rmanent magnet comprisinga ma etize l i ody of an alloy steel containingfr o r n 5 to per cent. cobalt substantially uniformly distributedtherethro h.

15. As a new artic e of manufacture,-a

- permanent magnet comprisinga magnetized body of 'analloy steedcontaining a substan tial percenta of cobalt substantially uniformlydistri uted 'therethrough.

In testimony whereof I hereuntoaflix my ature." slgn KOTARO

